Mobile terminal devices such as a cellular phone, a PHS (Personal Handy-phone System) and a PDA (Personal Digital Assistant) provided with a communication function are widely utilized as a device to which various functions are added in addition to communication. In such a device, products on each of which a GPS (Global Positioning System) function is mounted increase, and they are used for a navigation system for carrying out navigation by displaying a map. In such a navigation system, by using an acceleration sensor together in the mobile terminal device on which the GPS function is mounted, intuitive navigation coupled to a walking action becomes possible. In addition, the GPS can demonstrate a great deal of power in difficult navigation at an underground shopping area or within doors.
Moreover, a first proposal for using protection of data when a mobile terminal device falls down by utilizing an acceleration sensor to determine time to start transfer of the data has been made (see Japanese Patent Application Publication No. 2001-331281, Paragraphs 0033 to 0035, and FIG. 1, for example). In this first proposal, it is adapted so that, in the case where the mobile terminal device starts free fall due to any cause, the acceleration sensor detects this at an early stage, and data stored in a memory are transferred to a backup server before the device collides with the ground to be damaged. In the case where a mobile terminal device falls from a height of about one meter, it is well possible to detect the falling, to start communication with the backup server, and to transfer the data to the backup server in the interval because there is time of about 450 milliseconds before collision against the ground.
It has been proposed as a second proposal (see Japanese Patent Application Publication No. 2005-284657, Paragraphs 0004 and 0024, and FIG. 6, for example) to use an acceleration sensor mounted on a cellular phone for data transfer other than such data transfer in an emergency. This second proposal is one for solving a problem that, when a user is caused to read the content of a file within a mobile information terminal, it may be hardly viewed because a display section provided in the device is small in relation to a size. It uses the mobile information terminal itself as an input device such as a mouse. The acceleration sensor is provided in the input device, and this determines whether or not to be a predetermined posture. In the case where it is determined to be the predetermined posture, information stored in storage means is to be transferred to other device.